Polymeric compositions which are able to absorb and release volatile ingredients are well known in the art, in particular concerning perfume delivery.
GB1558960 from Nagae, describes a perfume emitting PVC film to be used in umbrellas.
U.S. Pat. No. 4,618,629 from T. Burnett & Co, Inc describes fragrance-emitting polyurethane foams which have a particulate fragrance-carrying resin incorporated in them. The resin can be selected from a list of polymers (polyolefins, polyester, PVC and similar, polyamides, cellulose polymers).
A common use of polymeric compositions for perfume delivery comprises for example air freshening devices. These are typically in the form of aqueous gels usually obtained from crosslinked polysaccharide polymers (starches, alginates or CMC) such as those described in GB2286531 from Kelco, U.S. Pat. No. 3,969,280 from Johnson & Johnson.
While these and other documents claim to provide long lasting delivery of volatile materials, they are still far from being fully satisfactory for a number of reasons.
Firstly, these polymeric compositions can normally incorporate and release a very limited amount of volatile material, in most cases not exceeding 10% of the total weight of the compositions.
Secondly these polymeric compositions are not able to release uniformly different components of the volatile material which have different volatilities. Given, for example, a perfume which can have more than 10 different components, the more volatile components will be released first and after some time only the less volatile notes would be perceptible, therefore the full perfume character would never be perceived by the user. Actually, the above mentioned polymeric compositions are commonly used to deliver simple perfumes, typically consisting of a single volatile substance such as citronellol as they are simply not capable to consistently deliver a more sophisticated perfume as is increasingly desired by the modern perfume industry.
Thirdly pure polymeric materials are difficult to transform and generally require high temperatures to be molded. Therefore whenever a volatile material is introduced in the melt, a large amount of said material is lost due to the high temperature.
The first and second problems have been partially addressed by Firmenich in U.S. Pat. No. 4,734,278 which describes shaped bodies of block polyether-amide based resins (e.g. Pebax™) that provide sustained release of volatile actives (perfumes, deodorants, insecticides etc). An improvement has been obtained by Atochem who in WO 9726020A1 describe improved fragrant resins made by Pebax™+ a complex perfume (i.e. more than 5 components). Such resins are able to deliver a complex perfume with a reduced separation of the volatile ingredients over time.
The third problem has been partially solved by the use of plasticizers which, as it is well known to those skilled in the art, allow the reduction of the processing temperature of polymeric mixtures. This solution has been applied e.g. from Avon in U.S. Pat. No. 4,552,693 which describes transparent fragrance-emitting articles obtained from compositions comprising a thermoplastic polyamide resin, a plasticizer/solvent system comprising a sulfonamide plasticizer, and a fragrance. The advantage of using a plasticizer in these compositions is the possibility of processing said compositions (molding, extruding, filming) at relatively low temperatures.
However prior art compositions are still not completely satisfactory as they still have a tendency to release a greater amount of the volatile ingredient at the first moment and to decrease the release rate with time. Also, although improved in comparison with previous compositions, they still do not release uniformly different components of the volatile material which have different volatilities. Therefore there is still a need for a polymeric material which is able to incorporate and sustainedly release volatile materials which are composed by several ingredients of different volatility for a long time and without separation of said ingredients during the release, and is also capable of being easily processed and formed into an article.